[Draft] Add alerts for repository mirroring
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Context https://gitlab.com/gitlab-org/gitlab/-/merge_requests/174976#note_2254822144 | https://gitlab.com/gitlab-org/gitlab/-/issues/372200
# Proposal: Initial Iteration
Currently, when a repository is being mirrored, users see a block of text on the Project overview page but nowhere else in Code. It would be useful to add this alert to the Repository page as well, and communicate this in a scalable way.
**Due to feedback below, we are re-approaching this design proposal and will add a new proposal when the time is appropriate.**
<table>
<tr>
<th>Current</th>
<th>Proposed</th>
</tr>
<tr>
<td>
**Project overview page**
Mirroring
{width="340" height="215"}
Mirroring + read-only repository
{width="350" height="223"}
Mirroring error
{width="1233" height="829"}
Mirroring error with pause
{width="1233" height="829"}
</td>
<td>
**Project overview page**
Mirroring
{width="334" height="223"}
Mirroring + read-only repository
{width="330" height="219"}
Mirroring error
{width="344" height="242"}
Mirroring error with pause
{width="375" height="265"}
</td>
</tr>
<tr>
<td>
**Repository page**
Mirroring
{width="1232" height="788"}
Mirroring + read-only repository
Mirroring error
Mirroring error with pause
{width="1230" height="787"}
</td>
<td>
**Repository page**
Mirroring
{width="394" height="280"}
Mirroring + read-only repository
{width="361" height="256"}
Mirroring error
{width="353" height="250"}
Mirroring error with pause
{width="355" height="252"}
</td>
</tr>
<tr>
<td>
**Settings page**
Mirroring
{width="1231" height="789"}
Mirroring + read-only repository
{width="1231" height="789"}
</td>
<td>
**Settings page**
Mirroring (no change)
{width="344" height="218"}
Mirroring + read-only repository
{width="367" height="292"}
Mirroring error
{width="402" height="320"}
Mirroring error with pause
{width="1200" height="957"}
</td>
</tr>
</table>
#### Design Feedback
* https://gitlab.com/gitlab-org/gitlab/-/issues/509463#note_2266620578
* Alerts should be reserved for information that users really need to know in that task/instance, and take up a large amount of screen real estate at the top
* Yellow/red alerts make sense because users need to be aware of errors
* Forks experience similar issues, in that many community contributors fork repositories but have a difficult time telling apart forked repositories from upstream repositories
#### Next Steps
* @alyssatrinh will have to re-approach the design to incorporate this feedback, and also find an elegant solution that works for mirrors and forks
* We will still use the alerts for error states, but they may be scaled down
issue